This application claims priority of Korea patent Application No. 2000-78384, filed on Dec. 19, 2000.
(a) Field of the Invention
The present invention relates to a planetary gear system used for an automatic transmission, and more particularly, to a pinion carrier assembly that carries pinion gears in a planetary gear system.
(b) Description of the Related Art
A conventional planetary gear system includes a sun gear and a ring gear with pinion gears engaged between the sun and ring gears. The pinion gears are connected to and carried by a pinion carrier assembly.
The pinion carrier assembly includes a pinion carrier body and pinion shafts, the pinion shafts being fixed to the pinion carrier body for rotatably supporting the pinion gears.
Various structures for fixing the pinion shaft to the pinion carrier body have been realized and a most typical one is such that a connecting hole is formed in each of the pinion shaft and pinion carrier body, where a locking pin engaged through the holes holds tight connection between the pinion shaft and the pinion carrier body.
However, the typical structure for fixing the pinion shaft to the pinion carrier body implies that a process for forming holes in the pinion shaft and the pinion carrier body and a locking pin are necessary in order to manufacture a pinion carrier assembly, which results in complications of manufacturing and an increase of time and cost for the manufacturing.
The present invention has been made in an effort to reduce time and cost for manufacturing a pinion carrier assembly, and it is an objective of the present invention to provide a pinion carrier assembly that has a structure that enables shortening manufacturing time and reducing a number of parts included in the pinion carrier assembly.
To achieve the above objective, the present invention provides a pinion carrier assembly that includes a pinion carrier body and a pinion shaft that is fixed to the pinion carrier body for rotatably supporting a pinion gear, wherein the pinion shaft is fixed to the pinion carrier body by calking.
Deformation grooves are formed in a calking portion of the pinion carrier body so that the calking portion of the pinion carrier body can be easily deformed toward the pinion shaft, and the deformation grooves are formed parallel to one another and in a direction tangential to the circumference of the pinion shaft.
The calking portion of the pinion shaft is indented so that the pinion shaft can also be deformed in order to accept the deformation of the calking portion of the pinion carrier body.
The indent formed in the pinion shaft is preferably a linear groove formed on the surface of the calking portion of the pinion shaft and/or a bevel around its edge.
More specifically, a penetration hole for receiving the pinion shaft is formed in an outer part of the pinion carrier body, the pinion shaft is inserted through the penetration hole and one end of the pinion shaft is sustained by an inner part of the pinion carrier body, and the outer part of the pinion carrier body is calked to the other end of the pinion shaft.